Paul Weitz, the director of the 1999 teen sex romp “American Pie,” is these days often referred to as a feminist filmmaker — a designation Mr. Weitz, 49, appears to politely demure.

“It wasn’t conscious on my part that almost all of the characters would be female; it just happened,” Mr. Weitz told The Washington Times of his new film, “Grandma.” “But also I was probably at the point where it wasn’t a big deal to me.”

“Grandma,” written and directed by Mr. Weitz, opens in the District Friday. Academy Award-nominee Lily Tomlin stars as Elle, a Los Angeles bohemian who one morning harshly breaks up with her lover, Olivia (Judy Greer). Only moments later, Elle is paid an unexpected visit by her teenage granddaughter, Sage (Julia Greer), with the news that she is pregnant.

Mr. Weitz said the germ of the idea for “Grandma” was twofold. One, he wanted to tell a story of an older character helping out a younger one, and in the process undergoing changes of her own. Secondly, he had worked with Miss Tomlin on his previous film “Admission,” in which she played the mother of the film’s star, Tina Fey.

“Just from hanging out with her, I was like, this person has so much more to offer than I’m calling on her to do in this movie,” he said, adding that he while penning “Grandma,” he continually heard Elle’s words in the voice of Miss Tomlin.

Mr. Weitz said it also appealed to him to have the main character be a woman in her mid-70s, who is the film’s anchor and for whom “there’s no deathbed scene,” in contrast to other movies where older characters are too easily dispatched for the sake of plot convenience.

In fact, in “Grandma,” Elle is anything but passive. Having recently shredded her own credit cards, Elle takes Sage on a “Ulysses”-like Odyssey of L.A. in the hunt for funds for the needed abortion. This includes a rather comedic confrontation with Sage’s loser boyfriend.

“She’s … a bull in a china shop and really funny,” Mr. Weitz said of his lead. “In this case I wanted to do something very, very simple. And I thought … that allowed the characters and the themes to become more and more complicated.”

All of this is light-years away from “American Pie,” which trafficked in adolescent sex gags like the infamous “pie scene.” However, Mr. Weitz said his intent with “American Pie,” as with “Grandma,” was to make films that appeal to women and that offer strong female protagonists.

“Actually, the girls in [‘American Pie’] are at all times in control in the scenes they’re in,” he said.

“I went to an all-boys school in New York City, which is another place where you’re not really going to learn a heck of a lot about, say, feminism or the idea that women are equal to men,” Mr. Weitz said, smiling. “So for me there’s been a distance traveled, but the great thing was I wasn’t consciously setting out to do a ‘woman’s movie’ or a ‘feminist movie,’ [with ‘Grandma’], it just sort of turned out that way.”

One of the strongest threads of feminist inquiry in “Grandma” revolves around the notion of the progress that American women have made, and of how quickly such gains can be forgotten by ensusing generations. Mr. Weitz points to a scene in “Grandma” where Elle attempts to sell a bookstore owner — played by the late Elizabeth Pena — several of her first-edition copies of works by Gloria Steinem and Betty Friedan.

“I loved the idea that at 18, the Julia Garner character had forgotten all this stuff that her grandmother had fought for,” Mr. Weitz explained. “One [scene] in the movie that’s very important to me is there’s an insult-fest between Lily Tomlin and Judy Greer, where they’re calling each other these very erudite insults like ‘writer in resident,’ ‘solipsist,’ etc. And then afterwards in this car, [Sage] says to [Elle], ‘You know, my friends just call each other “bitch” “ho” and “slut.”’”

Oscar-winner Marcia Gay Harden co-stars as Elle’s daughter, Judy, an emotionally distant but high-energy corporate lawyer who is first seen in her office on an exercise bike.

“I like the idea that Lily’s character was in the middle of fighting for [women’s equality and] her daughter Marcia Gay Harden was a product of it, probably mostly duking it out with male lawyers,” Mr. Weitz said.

“I liked that her alarms would be going off” when Elle and Sage show up at her office, he said. “It’s the middle of the day, [and] to have your teenager daughter and your mother show up, she knew something was afoot.”

Mr. Weitz has children of his own. One of the running themes of “Grandma” is how parents, no matter their age or their detractions, do they best they know how, no matter their pasts of present circumstances. Mr. Weitz recalls his own father, a German-Jewish immigrant to America who returned to Europe as a young man — this time as a soldier in the American Army during WWII.

“I remember at the end of his life, he said, ‘I didn’t know if I was going to be a decent dad to you and your brother,’” Mr. Weitz recalled, adding that the self-doubt of his own father infused his writing process for “Grandma.” “I really like the idea of people who are skeptical about themselves and really learn something in helping somebody,” he said.

Mr. Weitz believes that the oft-touted complaint that there aren’t enough strong roles for women in films is being chipped away at, and not only in arthouse films like “Grandma.” He points to the blockbuster “Hunger Games” films starring Jennifer Lawrence as but one example.

Mr. Weitz’s mother was an actress who stopped acting in the 1960s to have a family, but he described her choice as not one of resentment.

“While that was not considered a feminist thing to do, she completely owned her decision, and my dad was incredibly respectful of her intelligence,” he said.

Mr. Weitz’s grandmother, now a vibrant 105 years of age, was also an actress in her youth. He said his grandmother, much like Elle, is not one to back down from a conflict. Mr. Weitz proudly says she “still has a glass of tequila ever night. And her nickname in the family was ‘The General.’”

It’s been quite an arc for Mr. Weitz from his debut as the helmer of “American Pie,” although he still remains grateful that it launched his career as a director and that people continue to ask him about it. While he maintains he doesn’t want his own young children to see the gross-out comedy for some time, he would be OK if they did so when a little older.

“In order to grow as a filmmaker, I think sometimes you have to try stuff you’re going to fail at,” he said. “And I think ‘American Pie’ was successful at what it was attempting to be. But I try to remind myself that filmmakers I admire, like Billy Wilder or Preston Sturges, if you look at all theirs films, there are some ones that don’t live up to their great ones.”

Indeed, the final shot of “Grandma” even echoes one of Mr. Weitz’s heroes, John Ford, in its composition and mythology, almost as if Elle becomes part of the collective memory, much like John Wayne in one of Ford’s Westerns.

When asked if Miss Tomlin, long a strong icon of women’s equality and gay rights, might perhaps be a candidate to be the woman on the redesigned $20, Mr. Weitz smiles and laughs.

“Look, you have to be blind to not see that it would be great to have a woman on some denomination,” he said. “I think the great thing about Lily, and why she is so inherently youthful, is that … she represents cultural change and has for 50-some years.

“I think the great thing about her is not only does she represent change, but she represents that … we’re all just people, which is the stance of the movie.”